Former Wisconsin Gov. Tommy Thompson and businessman Eric Hovde hold solid leads over their opponents in the race for the GOP nomination for Wisconsin's open Senate seat, according to a Marquette University Law School poll released today. The survey is the latest in a string of news suggesting that Hovde and Thompson are the race's frontrunners.

The poll, which surveyed 432 likely GOP voters, shows Thompson leading Hovde with support from 35 percent of likely voters compared with Hovde's 23 percent. Former Rep. Mark Neumann and state Speaker Jeff Fitzgerald remained in a distant third and fourth place, respectively. Twenty-five percent of of likely voters said they remained undecided. The GOP primary portion of the poll had a margin of error of 4.8 points.

The Marquette poll is the latest evidence that the primary has narrowed to two primary competitors. A Public Policy Polling survey released Tuesday showed Hovde leading the former governor by 2 points. An internal poll from the Hovde campaign released last week showed him trailing Thompson by 5 points.

The opposition also seems to expect to face either Thompson or Hovde in the general election. EMILY's list released a television ad Tuesday that targets the pair and ignores the other GOP candidates. The ad buy has $400,000 behind it.

The general election portion of the poll, which surveyed 810 likely voters, showed presumptive Democratic nominee Rep. Tammy Baldwin behind Thompson by 4 points and defeating all of her other potential opponents. That section had a margin of error of 3.5 points.